Microscopy was used on heat treated duplex steels for microstructure identification.
FESEM–BSE observation on unetched samples provided the best contrast between phases.
Analyses of carbides, nitrides, chi and sigma phases were possible by EDS and WDS.
Chromium nitrides act as favorable site for the nucleation of chi and sigma phases.
Secondary phases nucleation kinetics are faster in superduplex than in duplex steels.